The invention relates to a flange yoke for a universal joint of a universally jointed shaft, comprising two joint fork halves and particularly relates to elements for causing the fork halves to act together under torque, and furthermore relates to a universally jointed shaft with a flange yoke.
A large number of embodiments of split flange yokes are known. Representative publications include:
1. EP 02 06 026 A1
2. DE 43 13 141 C2
Split joint forks make it possible to design one-piece dimensionally stable bearing lugs that, like joint forks that are not split, remain part of the adjoining fork arm via which power is transmitted to the bearing lug. This avoids interruption in the flow of power at those points on the joint fork that are subjected to the highest specific stresses. The dividing point, which is arranged in the plane of symmetry between the bearing lugs and the joint fork, lies in the region of low stress, which has no effect on power transmission. These arrangements have the advantages that the bearing arrangement is well embedded in the bearing lug, assembly is very easy and the bearing capacity of the bearing is increased. At the same time, split joint forks have considerable advantages for production, machining, transportation and storage.
In the embodiment described in EP 02 06 026 A1, each joint fork half has a flange, which has positive-locking elements on its side facing away from the axis of the spider. This forms a form-locking connection with the driven shaft or the shaft to be driven. In addition, releasable connections are provided between the flange and the respective shaft, by means of reduced-shank bolts, for example. The parting faces of the joint fork halves are arranged essentially parallel to one another, and they have mutually opposite keyseats in the central area. Square keys are inserted into these keyseats. These primarily prevent displacement of the individual joint fork halves relative to one another parallel to the pin axis of the respective pin supported in the joint fork. It is not possible to avoid relative motion of the joint fork halves perpendicular to the pin axis with this arrangement, nor can the joint fork halves be preloaded relative to one another. This permits undesirable lifting off of individual areas of the joint fork halves under the effect of the peripheral force, especially in reversing mode. Lifting off also has the effect of motion of the form-locking elements relative to the recesses on the adjoining shaft, which in turn leads to the formation of cavities, in which moisture and infiltrating surface water can collect. Corrosion phenomena result, which are accelerated by the micromovements of the joint fork halves.
To solve this problem, DE 43 13 141 C2 proposes an embodiment with end serrations on the underside of the flange and toothing in the region of the parting faces to provide a form-locking connection between the two joint fork halves. The toothing is preferably embodied as straight spur toothing with oblique flanks and is configured such that the extension of the tooth trace of the toothing or, where curved toothing is selected, of the secant through both end points of the tooth trace, forms an angle of from  greater than 0 degrees to  less than 180 degrees with a plane formed by the joint fork axis and the pin axis. The joint fork axis generally lies in the plane of symmetry between the two joint fork halves and is perpendicular to the pin axis of the pin supported in this joint fork. The term joint fork axis is here understood to mean the axis of rotation, which coincides with the axis of rotation of a universally jointed shaft. The preloading of the flanks virtually eliminates relative motion between the joint fork halves perpendicular to the pin axis. However, small cracks have been observed at the roots of the teeth in this embodiment after a prolonged period of operation. This damage occurs to a particularly great extent especially in embodiments of flange yokes having a closed fork lug, i.e. an integral blind hole to receive the bearing arrangement for the spider.
The invention therefore has the object of developing a flange yoke of the type stated above such that relative motion of the joint fork halves parallel to the joint fork axis is virtually eliminated, while avoiding damage to the individual elements of the flange yoke, particularly on the joint fork halves. The flange yoke should furthermore have a favorable configuration for the reception of the bearing arrangement and for achieving bearing forces which are as high as possible and should be economically producible, involving effective use of existing capacity and should be easy to assemble.
In the first embodiment, the flange yoke comprises two joint fork halves, which are complementary to one another and which abut one another along a coupling face that is essentially perpendicular to the pin axis of a spider pin supported by the joint fork. The phrase joint fork halves complementary to one another is to be understood to mean that they can cooperate with one another to form a complete structural unit, consisting of the joint fork, which performs the function of coupling to shafting as a flange yoke. Each joint fork half comprises a base component connectable to a shaft, for example, and a bearing component. Both joint fork halves can be connected in a form-locking manner to one another in the region of their base component to form one flange component from the individual base components.
The base components of the joint fork halves have mutually complementary first sets of toothing in the region of the outer circumferences on their coupling face, so that each coupling face faces the base component of the other joint fork half. The extension of a tooth trace (or direction of extension) of the toothing on the coupling face or of a plurality of tooth traces, or when the toothing is in the form of curved toothing, the extension of the secant through the end points of a tooth trace or the extensions of a multiplicity of secants, form an angle of from  greater than 0 degrees to  less than 180 degrees with a plane which is formed by the pin axis of the pin support ed in a joint fork half and by a joint fork axis coinciding with an axis of rotation of the joint fork. This first set of toothing is accordingly aligned in such a way that it can assume any position relative to the joint fork axis, with the exception, however, of a position parallel to the joint fork axis. Essentially, a distinction can be drawn between two cases:
1) The tooth traces of the toothing or their extension or, in the case of an embodiment with curved toothing, the secants through the end points of the tooth traces or their extensions, extend obliquely to a plane formed by the joint fork axis and a pin axis of a pin supported in the joint fork.
2) The tooth traces of the toothing or their extension or, in the case of embodiment as curved toothing, the secants through the end points of the tooth traces or their extensions, are parallel to this plane formed by the joint fork axis and the pin axis of the pin supported in the joint fork but, here too, parallel alignment of the first set of toothing to the joint fork axis is excepted.
In both cases, the tooth trace or its extension or the tangents intersect the joint fork axis once when the tooth traces or the tangents to the tooth traces and the joint fork axis are projected onto a common plane.
According to the invention, the first set of toothing is arranged only in that area of the coupling face that is radially toward the outside relative to the joint fork axis.
A further, second set of toothing is additionally provided in the more highly stressed regions of the joint fork halves. In this toothing, the fact that the extensions of one or more tooth traces of the second set of toothing or, in the case of an embodiment with curved toothing, the extensions of a secant through the end points of a tooth trace of the second set of toothing, are arranged at an angle of between 70 degrees and 110 degrees inclusive to the extension of a tooth trace of the first set of toothing or, in the case of curved toothing, to the extension of a secant through the end points of a tooth trace of the first set of toothing. The extensions of the tooth traces of the second set of toothing or, in the case of curved toothing, of the secants through the end points of the tooth trace, are preferably aligned essentially perpendicular to the tooth traces of the first set of toothing or the secants.
Means for clamping the two joint fork halves relative to one another are furthermore provided.
The provision of two sets of toothing aligned at an angle to one another on the coupling face of the two joint fork halves creates a form-locking connection between the joint fork halves which is self-centering in the axial direction in the installed position in shafting, in particular a universally jointed shaft. By means of the toothing, even very high forces can be compensated for without damage to the individual sets of toothing. This makes virtually impossible any movement essentially parallel to a plane formed by the joint fork axis and the pin axis of the other pin of a spider, which pin axis is aligned perpendicular to the pin axis of the pin supported in the joint fork. By virtue of the preloading of the flanks of the toothing, relative motion between the joint fork halves perpendicular to the pin axis, i.e. in the direction of the joint fork axis, is prevented. By virtue of the form-locking connection at the coupling faces of the joint fork halves, the opposing tensile and compressive stresses in one half of the connecting component are balanced in the connecting component, i.e. uniform load distribution is achieved over the entire cross section of the connecting component. Micromovements in the coupling between the connecting component and the flange yoke in the connection to the adjoining shaft are avoided. This avoids the formation of cavities in which infiltrating surface water and the like could accumulate. The additional mechanical stresses caused by relative motion, which could lead to acceleration of the corrosive effect at the points of contact, are thus likewise eliminated.
The first set of toothing can be embodied as spur toothing or curved toothing, for example. This applies analogously also to the second set of toothing. The second set of toothing is preferably embodied as straight spur toothing with a flank angle of between 10 and 60 degrees inclusive.
As regards the design of the second set of toothing on the coupling faces, toothing with a pitch in a range of from 8 to 20 inclusive in relation to the diameter of rotation of shafting coupled to the flange yoke of between 500 and 1000 cm inclusive is preferable to obtain the best possible load bearing pattern.
The two joint fork halves are preferably of essentially symmetrical construction. In that case, the coupling face of each joint fork half can be described by a plane. However, there is also the possibility of an asymmetric configuration of the base components of the two joint fork halves, i.e. the coupling face comprises partial areas that are arranged in different planes. In this case, one of the two joint fork halves can have a recess, for example, while the other joint fork half has the projection complementary to the recess, thereby precisely defining the position of the two joint fork halves relative to one another. The sets of toothing can then be arranged in the areas of the coupling face that are formed by the projections and recesses.
The means for force- and/or form-locking connection provided on the underside of the flange, which side faces away from the pin axis, for the purpose of torque transmission and centering, cooperating with means embodied in a manner complementary to them on the connection elements, which are preferably embodied as end serrations, the tooth traces of the serrations extending in a radial direction relative to the joint fork axis, and by virtue of additional screwed joints between the flange yoke and the connecting component, a self-centering and force-locking connection is additionally formed with the adjoining shaft or connecting component. This prevents movement of the joint fork halves relative to one another parallel to the pin axis of the pin supported in this joint fork or perpendicular to the joint fork axis.
The joint fork axis preferably lies in the plane of symmetry between the two joint fork halves and is perpendicular to the pin axis of the pin supported in the joint fork. The symmetry of the two joint fork halves is easy to achieve in terms of production, but is not compulsory.
The toothing is preferably embodied in such a way that, when projected onto one plane with the joint fork axis, the tooth traces or their extensions extend perpendicular to the joint fork axis and perpendicular to a plane formed by the joint fork axis and a pin axis of a pin supported in the joint fork. The size of the toothing on the parting faces will preferably be the same as that of the end serrations on the underside of the flange yoke. This provides the possibility of making more effective use of tools which are already available.
The second possibility for achieving the invention comprises cutting out a segment in those areas of the base components that are subject to little stress, before dividing the flange yoke, and providing a corresponding first set of toothing on the mutually complementary parting faces of the segment and the joint fork halves, as already described. The arrangement of the second set of toothing is produced in an analogous manner.
Other objects and feature of the invention are explained below with reference to the drawings.